Back when iPhone 3.0 launched, we heard Wi-Fi was giving problems to some -- primarily iPod touch -- users. Various network resets or OS restores seem to have quieted that down, but now TUAW is reporting that the newly launched iPhone 3GS might be suffering Wi-Fi troubles as well:

Users note that signal strength can fluctuate between one and full bars even when standing right next to the router or when a computer nearby shows a constant signal. This goes along with a commensurate reduction in speed.

Neither Jeremy nor I have been experiencing this, but if you have, let us know in the comments, along with what type of router you're running, and what kind of speed/connection quality you're getting (or not getting, more precisely).

(Wether this is, in fact, a widespread problem and one corrected by iPhone 3.1 we don't yet).